Radio communication apparatuses and radio communication method

ABSTRACT

Provided are a radio communication mobile station apparatus, a radio communication base station apparatus and a radio communication method, which make it possible to correctly switch between transmission modes for a PUSCH and a PUCCH while impeding signaling overhead from increasing. A transmission mode setting unit ( 107 ) detects an instruction given by a base station, the instruction indicating a multiplexing method for a PUSCH and a PUCCH. A trigger information reporting determination unit ( 108 ) performs threshold discrimination where PHR_pucch, which is calculated by PHR_control calculation unit ( 106 ), is compared with a threshold value that depends on the multiplexing method indicated by the instruction given by the base station. Specifically, in a TDM transmission mode, trigger information is reported if PHR_pucch&gt;X 1 [dBm] is satisfied. On the other hand, in an FDM transmission mode, the trigger information is reported if PHR_pucch&lt;Y 1 [dBm] is satisfied. Based on a result of the threshold discrimination, the trigger information reporting determination unit ( 108 ) determines whether to report the trigger information.

TECHNICAL FIELD

The present invention relates to a radio communication apparatus and aradio communication method.

BACKGROUND ART

In 3rd Generation Partnership Project Long-term Evolution (3GPP LTE), inthe case where a data channel (physical uplink shared channel (PUSCH))and a control channel (physical uplink control channel (PUCCH)) aretransmitted in the same subframe, a mobile station multiplexes the twochannels by time division multiplexing (TDM), as shown in FIG. 1. Thatis, data is punctured by control information such as an ACK or a NACK.By TDM multiplexing, it is possible to maintain single carriercharacteristics and prevent increase of cubic metric (CM). On the otherhand, because data is punctured, there is a problem that data receptionperformance deteriorates.

In an uplink channel of LTE-Advanced, which is an evolved version of3GPP LTE, in the case where a PUSCH and a PUCCH are transmitted in thesame subframe, a mobile station is expected to multiplex the twochannels by frequency division multiplexing (FDM), as shown in FIG. 2. Amobile station transmits a PUSCH and a PUCCH at the same time by mappingthe PUSCH and the PUCCH in different frequency bands. Because data isnot punctured by FDM multiplexing, it is possible to preventdeterioration of reception performance. On the other hand, there is aproblem that single carrier characteristics are not maintained andmulticarrier transmission is performed, so that CM increases. When CMincreases, the maximum transmission power that can be transmitted by amobile station lowers, so that power head room (hereinafter referred toas “power head room (PHR)”) of a mobile station located, for example, atthe cell edge, becomes small, and it becomes not possible to set thetransmission power required by a base station, lowering the receptionperformance of the base station significantly. PHR refers to the marginof transmission power of a mobile station or transmission power of amobile station that can be increased.

A method of multiplexing a PUSCH and a PUCCH at a mobile station, thatis, a method in which a base station controls whether to performmultiplexing by TDM (hereinafter referred to as “TDM transmission mode”)or perform multiplexing by FDM (hereinafter referred to as “FDMtransmission mode”) based on the PHR of a mobile station, is underconsideration (for example, see Non-Patent Literature 1). Specifically,in the case where the PHR of a mobile station is large (that is, themargin of transmission power is large), a base station applies the FDMtransmission mode, which does not subject to the influence of increaseof CM, so as to prevent deterioration of PUSCH reception performance.Further, in the case where the PHR of a mobile station is small (thatis, the margin of transmission power is small), a base station appliesthe TDM transmission mode, so as to prevent increase of CM and preventdeterioration of PUSCH reception performance.

Non-Patent Literature 1 discloses that, in the case of applying the FDMtransmission mode, it is necessary to preferentially ensure transmissionpower of a PUCCH, for which retransmission control processing is notperformed so as to require higher quality, compared to a PUSCH. That is,in the FDM transmission mode, when setting the ratio of transmissionpower of a PUSCH to a PUCCH, transmission power of the PUCCH is ensuredfirst, and transmission power of a PUSCH is set within the range of theremaining transmission power. By this means, it is possible to preventdeterioration of performance of a PUCCH, which requires higher quality.

Here, the definitions and methods of reporting of PHRs used in LTE willbe described below. In LTE, as shown in FIG. 3, only PHR that isdetermined based on transmission power of a PUSCH as a reference, isdefined. In LTE, a base station uses PHR to control the transmissionbandwidth and the modulation and channel coding scheme (MCS) of a PUSCHof a mobile station. A base station can receive a PUSCH with a receptionquality desired by the base station, by controlling the transmissionbandwidth and MCS of a PUSCH of a mobile station so that transmissionpower of a PUSCH to be transmitted by a mobile station does not exceedthe maximum transmission power of the mobile station.

Non-Patent Literature 2 discloses the definition of PHR and thetransmission condition of PHR by equation 1.PHR_pusch=Pmax−Ppusch  (Equation 1)

In equation 1, PHR_pusch is PHR [dB] based on a PUSCH, and Pmax is themaximum transmission power [dBm] of a mobile station. Ppusch of equation1 is transmission power of a PUSCH and is defined by following equation2.Ppusch=10 log₁₀ M+P ₀+α·PL+Δ_(MCS) +f(Δ_(i))  (Equation 2)

In equation 2, M is the number of frequency resource blocks to beassigned, P₀ is a value [dBm] set from a base station, PL is a path losslevel [dB] measured by a mobile station, α is a weighted coefficient toshow the compensation rate of path loss, Δ_(MCS) is an offset dependingon the MCS, and f(Δ_(i)) is a transmission power control value for whichclosed loop control is performed (for example, relative values of +3 dBor −1 dB) and is the result of addition including the past transmissionpower control value.

P₀, α, and Δ_(MCS) are parameters to be reported from a base station toa mobile station, and are values that are known by a base station. Onthe other hand, PL and f(Δ_(i)) are values that cannot be knowncorrectly by a base station. Although f(Δ_(i)) is a parameter to bereported from a base station to a mobile station, there is a case wherea mobile station cannot receive that command (cannot detect a controlchannel (PDCCH)). Because a base station cannot determine whether or nota mobile station can correctly receive a command, once a mobile stationfails to receive a transmission power control value from a base station,a discrepancy of recognition between the mobile station and the basestation occurs. As described above, because a base station cannot knowPHR of a mobile station correctly, PHR needs to be reported from amobile station.

PHR is reported from a mobile station in a cycle determined by a basestation in advance. PHR is reported as medium access control (MAC)information of transmission data by a PUSCH using six bits.

CITATION LIST Non-Patent Literature

NPL 1

-   3GPP R1-090611, Samsung, “Concurrent PUSCH and PUCCH Transmissions”    NPL 2-   3GPP TS36.213 V8.5.0 7.1.6.1 Resource allocation type 0, “Physical    layer procedures (Release 8)”

SUMMARY OF INVENTION Technical Problem

However, a base station cannot correctly switch from the TDMtransmission mode to the FDM transmission mode, only by using theabove-described PHR based on a PUSCH (hereinafter referred to as“PHR_pusch”). This is because, in the FDM transmission mode, a basestation cannot control the transmission bandwidth and MCS of a PUSCH sothat transmission power does not exceed the maximum transmission powerof a mobile station, only by using PHR_pusch. This will be describedbelow.

In the FDM transmission mode, as described above, it is necessary topreferentially ensure PUCCH transmission power. That is, it is necessaryto control transmission power of a PUSCH, which is determined bycontrolling the transmission bandwidth and MCS of the PUSCH, within therange of PHR that is determined based on transmission power of a PUCCHas a reference (hereinafter referred to as “PHR_pucch”). When thetransmission power of a PUSCH that is required by a base station exceedsPHR_pucch of a mobile station, transmission power required forconcurrent transmission of a PUSCH and a PUCCH exceeds the maximumtransmission power of the mobile station, so that the mobile stationcannot transmit a PUSCH with the transmission power required by the basestation. Therefore, it becomes not possible to receive a PUSCH with thedesired reception quality assumed by the base station, lowering thereception performance of a PUSCH.

For this reason, it is desirable that PHR_pucch, in addition toPHR_pusch, is reported from a mobile station to a base station. However,in the case where PHR_pucch is simply reported in addition to PHR_pusch,signaling overhead doubles as shown in the sequence diagram of FIG. 4.Because PHR of LTE is reported per dB in the range of −23 to 40 dB, theamount of signaling required for one PHR is six bits, as shown in FIG.4.

On the other hand, in LTE, transmission powers of a PUSCH and a PUCCHare controlled separately. Therefore, it is not possible to correctlydetermine PHR_pucch from PHR_pusch. Further, in the case of calculatingPHR_pucch in a base station, there is a following problem.

PHR_pucch is defined by following equation 3. Further, Ppucch ofequation 3 is transmission power of a PUCCH, and is defined by equation4.PHR_pucch=Pmax−Ppucch  (Equation 3)Ppucch=P ₀ _(—) _(pucch)+PL+h+Δ _(pucch) ±g(Δ_(i))  (Equation 4)

In equation 4, P₀ _(—) _(pucch) is a value [dBm] set by a base station,h and Δ_(pucch) are values determined depending on the transmissionformat of a PUCCH, and g(Δ_(i)) is a transmission power control valuefor which closed loop control is performed and is the result of additionincluding the past transmission power control value. Because PL is theresult measured by a mobile station, a base station cannot know PL.Further, regarding g(Δ_(i)), as is the case with f(Δ_(i)) in equation 2,a base station cannot determine whether or not a mobile station couldrecognize a command correctly.

Therefore, if making a mobile station report PHR_pucch so that a basestation can know PHR_pucch correctly, the amount of signaling increases.On the other hand, if the amount of signaling is suppressed, a basestation cannot know PHR_pucch correctly, and in the FDM transmissionmode, it is not possible to control the transmission power of a PUSCHwithin the range of PHR_pucch so that transmission power does not exceedthe maximum transmission power of a mobile station.

It is therefore an object of the present invention to provide a radiocommunication apparatus and a radio communication method for making itpossible to suppress increase of signaling overhead and correctly switchtransmission modes of a PUSCH and a PUCCH, at the same time.

Solution to Problem

A radio communication apparatus according to the present inventionemploys a configuration to include: a trigger information reportdetermination section that determines whether or not to report triggerinformation that induces switch of a time division multiplexingtransmission mode and a frequency division multiplexing transmissionmode, which are methods of multiplexing a shared channel and a controlchannel, to a communicating party apparatus; and a transmission sectionthat transmits the trigger information to the communicating partyapparatus, when the trigger information is determined to be transmitted.

A radio communication apparatus according to the present inventionemploys a configuration to include: a trigger information detectionsection that detects trigger information that induces switch of a timedivision multiplexing transmission mode and a frequency divisionmultiplexing transmission mode, which are methods of multiplexing ashared channel and a control channel, from a signal transmitted from acommunicating party apparatus; a transmission mode control section thatswitches a transmission mode to be used for next transmission by thecommunicating party apparatus, based on the detected triggerinformation; and a transmission section that transmits transmission modeorder information that orders switch of the transmission mode, to thecommunicating party apparatus, when switching the transmission mode.

A radio communication method according to the present invention employsa configuration to include the methods of: determining whether or not toreport trigger information that induces switch of a time divisionmultiplexing transmission mode and a frequency division multiplexingtransmission mode, which are methods of multiplexing a shared channeland a control channel, to a communicating party apparatus; andtransmitting the trigger information to the communicating partyapparatus, when the trigger information is determined to be transmitted.

A radio communication method according to the present invention employsa configuration to include the methods of: detecting trigger informationthat induces switch of a time division multiplexing transmission modeand a frequency division multiplexing transmission mode, which aremethods of multiplexing a shared channel and a control channel, from asignal transmitted from a communicating party apparatus; switching atransmission mode to be used for next transmission by the communicatingparty apparatus, based on the detected trigger information; andtransmitting transmission mode order information that orders switch ofthe transmission mode, to the communicating party apparatus, whenswitching the transmission mode.

Advantageous Effects of Invention

According to the present invention, it is possible to suppress increaseof signaling overhead and correctly switch transmission modes of a PUSCHand a PUCCH at the same time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a condition where a PUSCH and a PUCCH are TDM transmitted;

FIG. 2 shows a condition where a PUSCH and a PUCCH are FDM transmitted;

FIG. 3 shows PHR that is determined based on transmission power of aPUSCH as a reference;

FIG. 4 shows a condition where signaling overhead is increasing;

FIG. 5 is a block diagram showing a configuration of a mobile stationaccording to Embodiment 1 of the present invention;

FIG. 6 is a block diagram showing an internal configuration of the TDMsignal generation section shown in FIG. 5;

FIG. 7 is a block diagram showing an internal configuration of the FDMsignal generation section shown in FIG. 5;

FIG. 8 is a block diagram showing a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 9 is a block diagram showing an internal configuration of the TDMsignal demultiplexing section shown in FIG. 8;

FIG. 10 is a block diagram showing an internal configuration of the FDMsignal demultiplexing section shown in FIG. 8;

FIG. 11 is a sequence diagram showing a condition where the mobilestation shown in FIG. 5 transmits PHR_pusch and trigger information(PHR_pucch) to the base station shown in FIG. 8;

FIG. 12 is a sequence diagram showing a case where trigger informationshown in FIG. 11 is flag information of one bit showing the result ofcomparison with a threshold value;

FIG. 13 is a sequence diagram showing a condition where PHR_pusch andtrigger information, which is flag information of one bit, are reported;

FIG. 14 is a block diagram showing a configuration of a mobile stationaccording to Embodiment 2 of the present invention;

FIG. 15 is a sequence diagram showing a condition where the mobilestation shown in FIG. 14 transmits PHR_pusch and trigger information(PHR_pucch) to the base station shown in FIG. 8;

FIG. 16 is a block diagram showing a configuration of a mobile stationaccording to Embodiment 3 of the present invention; and

FIG. 17 is a sequence diagram showing a condition where the mobilestation shown in FIG. 16 transmits PHR_pusch and trigger information(PHR_pusch+pucch) to the base station shown in FIG. 8.

DESCRIPTION OF EMBODIMENTS

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. In embodiments, the sameparts will be assigned the same reference numerals and overlappingexplanations will be omitted.

Embodiment 1

FIG. 5 shows a configuration of radio communication mobile stationapparatus 100 (hereinafter simply referred to as “mobile station”)according to Embodiment 1 of the present invention. In this figure, RFreception section 102 performs reception processing, such asdown-conversion and A/D conversion, on a signal received via antenna101, and outputs the reception-processed signal to demodulation section103.

Demodulation section 103 demodulates scheduling information and a pilotsignal that are contained in the reception signal output from RFreception section 102, and outputs the demodulated schedulinginformation to PHR_data calculation section 104, PHR_control calculationsection 106, and transmission mode setting section 107. Further,demodulation section 103 outputs the demodulated pilot signal toPHR_data calculation section 104 and PHR_control calculation section106.

PHR_data calculation section 104 calculates PHR_pusch (PHR based on aPUSCH) by performing calculation of equation 1 based on, for example, apath loss level measured using the downlink pilot signal output fromdemodulation section 103, the number of frequency resource blocks of aPUSCH, the MCS, and power control information of a PUSCH that arecontained in the scheduling information output from demodulation section103, and outputs the calculated PHR_pusch to PHR_data reportdetermination section 105.

PHR_data report determination section 105 determines whether or not toreport the PHR_pusch output from PHR_data calculation section 104, to abase station, based on cycle T [ms] determined by the base station inadvance. That is, in the case where more than T [ms] has passed from theprevious report of PHR_pusch, PHR_pusch will be reported, and in thecase where more than T [ms] has not passed from the previous report ofPHR_pusch, PHR_pusch will not be reported. Upon determining to reportPHR_pusch, PHR_data report determination section 105 outputs PHR_puschto data generation section 109.

PHR_control calculation section 106 calculates PHR_pucch (PHR based on aPUCCH) by performing calculation of equation 3, based on, for example, apath loss level measured using the downlink pilot signal output fromdemodulation section 103, and power control information of a PUCCHcontained in the scheduling information output from demodulation section103, and outputs the calculated PHR_pucch to trigger information reportdetermination section 108.

Transmission mode setting section 107 detects a command of a method ofmultiplexing a PUSCH and a PUCCH (TDM transmission mode or FDMtransmission mode) that is contained in the scheduling informationoutput from demodulation section 103, and outputs the detection resultto trigger information report determination section 108 and switchsection 111.

Trigger information report determination section 108 compares which oneof PHR_pucch output from PHR_control calculation section 106 and apredetermined threshold value is smaller or greater, i.e. comparisonwith a threshold value. Trigger information report determination section108 determines whether or not to report trigger information, based onthe result of the comparison with of a threshold value. Here, thecondition of comparison with a threshold value is changed according tothe transmission mode output from transmission mode setting section 107.Here, trigger information is PHR_pucch or flag information showingwhether PHR_pucch is greater or smaller than a threshold value. As aresult of the comparison with a threshold value, upon determining toreport trigger information, trigger information report determinationsection 108 outputs trigger information to data generation section 109.Trigger information report determination section 108 will be describedlater.

Data generation section 109 generates data to be transmitted by mobilestation 100. Further, upon receiving PHR_pusch output from PHR_datareport determination section 105, or upon receiving PHR_pusch or triggerinformation output from trigger information report determination section108, data generation section 109 generates data including that PHR_puschor that trigger information, and outputs the generated data to switchsection 111.

Control information generation section 110 generates control information(for example, CQI, or ACK or NACK information) to be transmitted bymobile station 100, and outputs the generated control information toswitch section 111.

Switch section 111 switches whether to TDM transmit or FDM transmit thedata output from data generation section 109 and the control informationoutput from control information generation section 110, according to thecommand from transmission mode setting section 107. Upon receiving acommand of the TDM transmission mode from transmission mode settingsection 107, switch section 111 outputs the data and the controlinformation to TDM signal generation section 112. On the other hand,upon receiving a command of FDM transmission from transmission modesetting section 107, switch section 111 outputs the data and the controlinformation to FDM signal generation section 113.

TDM signal generation section 112 generates a TDM signal by timemultiplexing the data and control information that are output fromswitch section 111, and outputs the TDM signal to CP addition section114. TDM signal generation section 112 will be described in detaillater.

FDM signal generation section 113 generates a FDM signal by frequencymultiplexing the data and control information that are output fromswitch section 111, and outputs the FDM signal to CP addition section114. FDM signal generation section 113 will be described in detaillater.

CP addition section 114 copies part of the rear end of the signal outputfrom TDM signal generation section 112 or FDM signal generation section113, as a CP, and adds the CP to the front of that signal. The CP-addedsignal is output to RF transmission section 115.

RF transmission section 115 performs transmission processing, such asD/A conversion, amplification, and up-conversion, on the signal outputfrom CP addition section 114, and transmits the transmission-processedsignal to a base station from antenna 101.

FIG. 6 is a block diagram showing an internal configuration of the TDMsignal generation section 112 shown in FIG. 5. In this figure,multiplexing section 121 multiplexes the data and control informationthat are output from switch section 111 in the time domain, i.e. TDMmultiplexes, and outputs the TDM-multiplexed signal to discrete fouriertransform (DFT) section 122.

DFT section 122 performs DFT processing on the multiplexed signal outputfrom multiplexing section 121 and outputs the DFT-processed multiplexedsignal to mapping section 123.

Mapping section 123 maps the signal output from DFT section 122 on thefrequency band scheduled by a base station, and outputs the mappedsignal to inverse discrete fourier transform (IDFT) section 124.

IDFT section 124 performs IDFT processing on the frequency domain signaloutput from mapping section 123, converts the signal into a time domainsignal, and outputs the time domain signal to CP addition section 114.

FIG. 7 is a block diagram showing an internal configuration of FDMsignal generation section 113 shown in FIG. 5. In this figure, DFTsection 131 performs DFT processing on the data output from switchsection 111 and outputs the DFT-processed data to mapping section 132.

Mapping section 132 maps the data signal output from DFT section 131 andthe control information output from switch section 111 on the frequencyband scheduled by the base station, multiplexes the mapped data signaland control information in the frequency domain, i.e. FDM multiplexes,and outputs the FDM-multiplexed signal to IDFT section 133.

IDFT section 133 performs IDFT processing on the frequency domain signaloutput from mapping section 132, converts the signal into a time domainsignal, and outputs the time domain signal to CP addition section 114.

FIG. 8 is a block diagram showing a configuration of radio communicationbase station apparatus 200 (hereinafter simply referred to as “basestation”) according to Embodiment 1 of the present invention. In thisfigure, RF reception section 202 receives a signal transmitted frommobile station 100 via antenna 201, performs reception processing, suchas down-conversion and A/D conversion, on the received signal, andoutputs the reception-processed signal to CP removal section 203.

CP removal section 203 removes the CP of the signal output from RFreception section 202 and outputs the signal without a CP to switchsection 204.

Switch section 204 switches whether to demultiplex the data and thecontrol information in the time domain or demultiplex the data and thecontrol information in the frequency domain, according to thetransmission mode reported to mobile station 100. When having reported acommand of TDM transmission mode to mobile station 100, switch section204 outputs the signal without a CP to TDM signal demultiplexing section205, and when having reported a command of FDM transmission mode tomobile station 100, switch section 204 outputs the signal without a CPto FDM signal demultiplexing section 206.

TDM signal demultiplexing section 205 demultiplexes the data and thecontrol information in the time domain, and outputs the demultiplexedcontrol information to control information decoding section 207 andoutputs the demultiplexed data to data decoding section 208. TDM signaldemultiplexing section 205 will be described in detail later.

FDM signal demultiplexing section 206 demultiplexes the data and thecontrol information in the frequency domain, and outputs thedemultiplexed control information to control information decodingsection 207 and outputs the demultiplexed data to data decoding section208. FDM signal demultiplexing section 206 will be described in detaillater.

Control information decoding section 207 decodes the control informationoutput from TDM signal demultiplexing section 205 or FDM signaldemultiplexing section 206 to obtain the control information transmittedfrom mobile station 100.

Data decoding section 208 decodes the data output from TDM signaldemultiplexing section 205 or FDM signal demultiplexing section 206, andoutputs the decoded data to trigger information detection section 209.

Trigger information detection section 209 detects trigger informationcontained in the data output from data decoding section 208, and outputsthe detected trigger information to transmission mode control section210.

Transmission mode control section 210 determines to switch the method ofmultiplexing the data (PUSCH) and the control information (PUCCH) thatare to be transmitted from mobile station 100, using the triggerinformation output from trigger information detection section 209. Uponchange from the previous transmission mode, transmission mode controlsection 210 outputs transmission mode order information to switchsection 204 and modulation section 211. Transmission mode controlsection 210 will be described in detail later.

Modulation section 211 modulates the transmission mode order informationoutput from transmission mode control section 210, and outputs themodulated signal to RF transmission section 212.

RF transmission section 212 performs transmission processing, such asD/A conversion, amplification, and up-conversion, on the modulatedsignal output from modulation section 211, and transmits thetransmission-processed signal to mobile station from antenna 201.

FIG. 9 is a block diagram showing an internal configuration of TDMsignal demultiplexing section 205 shown in FIG. 8. In this figure, DFTsection 221 performs DFT processing on the reception signal without a CPthat is output from switch section 204, and outputs the signal convertedfrom the time domain to the frequency domain, to demapping section 222.

Demapping section 222 extracts a reception signal of desired mobilestation 100 from the frequency band scheduled by base station 200, outof the frequency domain signals output from DFT section 221, and outputsthe extracted reception signal to equalization section 223.

Equalization section 223 calculates a channel estimation value from apilot signal contained in the reception signal output from demappingsection 222. Equalization section 223 performs equalization processingfor correcting changes of the amplitude and the phase in the frequencydomain that the reception signal output from demapping section 222received in the channel, using the channel estimation value, and outputsthe reception signal after equalization processing to IDFT section 224.

IDFT section 224 performs IDFT processing on the reception signal outputfrom equalization section 223, converts the IDFT-processed receptionsignal into a time domain signal, and outputs the time domain signal todemultiplexing section 225.

Demultiplexing section 225 demultiplexes the reception signal outputfrom IDFT section 224 into control information and data in the timedomain, and outputs the demultiplexed control signal to controlinformation decoding section 207 and outputs the demultiplexed data todata decoding section 208.

FIG. 10 is a block diagram showing an internal configuration of FDMsignal demultiplexing section 206 shown in FIG. 8. In this figure, DFTsection 231 performs DFT processing on the reception signal without a CPthat is output from switch section 204, and outputs the signal convertedfrom the time domain to the frequency domain, to demapping section 232.

Demapping section 232 extracts data and control information of areception signal of desired mobile station 100 from the frequency bandscheduled by base station 200, out of the frequency domain signalsoutput from DFT section 231, and outputs the extracted data to firstequalization section 233 and outputs the extracted control informationto second equalization section 234.

First equalization section 233 calculates a channel estimation valuefrom a pilot signal contained in the reception signal output fromdemapping section 232. First equalization section 233 performsequalization processing for correcting changes of the amplitude and thephase in the frequency domain that the control information output fromdemapping section 232 received in the channel, using the channelestimation value, and outputs the obtained control information tocontrol information decoding section 207.

Second equalization section 234 calculates a channel estimation valuefrom a pilot signal contained in the reception signal output fromdemapping section 232. Second equalization section 234 performsequalization processing for correcting changes of the amplitude and thephase in the frequency domain that the data output from demappingsection 232 received in the channel, using the channel estimation value,and outputs the obtained data to IDFT section 235.

IDFT section 235 performs IDFT processing on the data output from secondequalization section 234, converts the IDFT-processed data into a timedomain signal, and outputs the time domain signal to data decodingsection 208.

Next, trigger information report determination section 108 shown in FIG.5 will be described in detail below. Trigger information reportdetermination section 108 performs comparison with a threshold valuewith respect to PHR_pucch of mobile station 100 that is calculated bymobile station 100, to determine whether or not to report triggerinformation.

Specifically, in the TDM transmission mode, trigger information isreported when equation 5 is satisfied. X1 is transmission power requiredfor a PUSCH having the greatest (highest quality required) MCS, forexample, in the maximum transmission bandwidth assumed. This is set inadvance at mobile station 100 by base station 200. By this means, whenequation 5 is satisfied, even when a PUSCH and a PUCCH are FDMtransmitted, it is possible to prevent transmission power of mobilestation 100 from exceeding the maximum transmission power (P_max).PHR_pucch>X1[dBm]  (Equation 5)Further, in the FDM transmission mode, trigger information is reportedwhen equation 6 is satisfied. Y1 is set as the same value as X1, forexample. By this means, when equation 6 is satisfied, even when a PUSCHand a PUCCH are FDM transmitted, it is possible to prevent transmissionpower of mobile station 100 from exceeding maximum transmission power(P_max).PHR_pucch<Y1[dBm]  (Equation 6)

Further, it is possible to set Y1 as a different value from X1. When Y1and X1 are the same value, reports of trigger information occurfrequently at mobile station 100 having the PHR_pucch that moves up anddown around the threshold value. By making a difference between Y1 andX1, it is possible to prevent the above-described frequent reports oftrigger information.

Further, trigger information to be reported can be PHR_pucch itself, orflag information of one bit showing whether PHR_pucch is greater orsmaller than a threshold value. In the case where PHR_pucch is set astrigger information, although the amount of signaling increases, byreporting PHR_pucch correctly, base station 200 can switch thetransmission mode more correctly and control the transmission bandwidthand MCS of a PUSCH. On the other hand, in the case where flaginformation of one bit is set as trigger information, although switchcontrol of the transmission mode becomes less accurate, it is possibleto reduce signaling overhead. Here, by controlling the transmissionbandwidth and MCS of a PUSCH within the range assumed upon setting X1 orY1, it is possible to prevent transmission power of a mobile stationfrom exceeding the maximum transmission power, even after switch of thetransmission mode.

Next, transmission mode control section 210 shown in FIG. 8 will bedescribed in detail below. Transmission mode control section 210determines to switch the method of multiplexing data (PUSCH) and controlinformation (PUCCH) that are to be transmitted next time by mobilestation 100, using the trigger information reported from mobile station100.

Specifically, in the case where mobile station 100 is in the TDMtransmission mode, when base station 200 obtains trigger informationreported from mobile station 100 by satisfying equation 5, transmissionmode control section 210 appropriately switches the transmission mode ofmobile station 100 from the TDM transmission mode to the FDMtransmission mode. In the condition where base station 100 reportstrigger information in the TDM transmission mode, even when thetransmission mode is switched to the FDM transmission mode, it ispossible to prevent transmission power of mobile station 100 fromexceeding the maximum transmission power (P_max).

Further, in the case where mobile station 100 is in the FDM transmissionmode, when base station 200 obtains trigger information reported frommobile station 100 by satisfying equation 6, transmission mode controlsection 210 appropriately switches the transmission mode of mobilestation 100 from the FDM transmission mode to the TDM transmission mode.In the condition where mobile station 100 reports trigger information inthe FDM transmission mode, by switching the transmission mode to the TDMtransmission mode, it is possible to prevent transmission power ofmobile station 100 from exceeding the maximum transmission power(P_max).

Next, the cycle in which mobile station 100 reports PHR_pusch, will bedescribed below. First, because the uses of PHR_pusch and PHR_pucch aredifferent, by reporting PHR_pusch or PHR_pucch according to thefrequency and accuracy corresponding to the use, it is possible tosuppress increase of signaling overhead and appropriately switch thetransmission mode at the same time.

As the use of PHR_pusch, PHR_pusch is used to control the transmissionbandwidth and MCS of a PUSCH so that transmission power does not exceedthe maximum transmission power of mobile station 100. On the other hand,as the use of PHR_pucch, PHR_pucch is used to determine to switch thetransmission mode (TDM transmission mode or FDM transmission mode).Because the transmission bandwidth and MCS of a PUCCH are fixed, it isnot necessary to control the transmission band and the MCS unlike aPUSCH.

Therefore, it is not necessary to report PHR_pucch that is used toswitch the transmission mode as frequently and accurately as PHR_pusch.Only when mobile station 100 can switch the transmission mode or needsto switch the transmission mode, base station 200 can switch thetransmission mode appropriately by reporting PHR_pucch to base station200.

FIG. 11 is a sequence diagram showing a condition where mobile station100 shown in FIG. 5 transmits PHR_pusch and trigger information(PHR_pucch) to base station 200 shown in FIG. 8. Base station 200 canknow information about PHR_pucch of mobile station 100 from triggerinformation, so that, in the TDM transmission mode, transmission powerof mobile station 100 does not exceed the maximum power, making itpossible to switch the transmission mode to the FDM transmission modeappropriately. Further, in the FDM transmission mode, it is possible toswitch the transmission mode to the TDM transmission mode appropriately,before transmission power of mobile station 100 exceeds the maximumpower. Compared to FIG. 4, it is clear that increase of signalingoverhead is suppressed. As described above, by reporting triggerinformation only when it is possible or necessary to switch thetransmission mode, it is possible to suppress increase of signalingoverhead.

Further, FIG. 12 is a sequence diagram showing a case where triggerinformation shown in FIG. 11 is flag information of one bit showing theresult of comparison with a threshold value. As shown in this figure, bysetting trigger information as flag information of one bit showing theresult of comparison with a threshold value, although switch control ofthe transmission mode becomes less accurate compared to the case wheretrigger information is PHR_pucch, it is possible to further suppressincrease of signaling overhead.

As described above, according to Embodiment 1, by performing comparisonwith a threshold value by changing the condition of the comparison witha threshold value of PHR_pucch of a mobile station, according to the TDMtransmission mode or the FDM transmission mode, which are methods ofmultiplexing a PUSCH and a PUCCH adopted by the mobile station, andreporting trigger information that induces switch between the TDMtransmission mode and the FDM transmission mode from the mobile stationto a base station according to the result of the comparison with athreshold value, it is possible to suppress increase of signalingoverhead and correctly switch the transmission mode.

Here, in the conditional expressions of equation 5 and equation 6, it ispossible to use PHR_pucch+pucch (PHR calculated based on transmissionpower required when a data channel and a control channel are FDMtransmitted, as a reference) defined in following equation 7, instead ofPHR_pucch.PHR_pusch+pucch=Pmax−(Ppusch+Ppucch)  (Equation 7)

Because it is possible to estimate PHR_pucch from the two pieces of PHRinformation of PHR_pusch+pucch and PHR_pusch, it is possible to obtainan equivalent effect to the case of reporting PHR_pucch.

Here, in the case of using PHR_pusch+pucch, it is necessary to use adifferent threshold value from the threshold values of equation 5 andequation 6 that use PHR_pucch. That is, in the TDM transmission mode,comparison with a threshold value is performed based on followingequation 8, and in the FDM transmission mode, comparison with athreshold value is performed based on following equation 9.PHR_pusch+pucch>X2[dBm]  (Equation 8)PHR_pusch+pucch<Y2[dBm]  (Equation 9)

X2 of equation 8 needs to be set as a greater value than X1 of equation5. For example, X2 is set as a value that is determined by addingtransmission power required for a PUSCH having the maximum transmissionbandwidth that can be assumed for X1. Further, Y2 of equation 9 needs tobe set as a greater value than Y1 of equation 6.

Although it is possible to set the same value for X2 and Y2, by settinga difference between X2 and Y2 to set different values, as is the casewith the above-described relationship between X1 and Y1, a mobilestation having the PHR_pusch+pucch that moves up and down around thethreshold value can prevent frequent reports of trigger information.

As shown in the sequence diagram of FIG. 13, regarding the condition inwhich trigger information report determination section 108 reportstrigger information, it is possible to set trigger information to outputas flag information of one bit showing the result of comparison with athreshold value, as is the case with conventional PHR_pusch. Compared toFIG. 4, it is clear that increase of signaling overhead is suppressed.Further, because the number of signaling bits is constantly the same(constantly seven bits in the figure), it is possible to use onesignaling transmission format, making it possible to simplify processingof a mobile station and a base station.

Embodiment 2

FIG. 14 is a block diagram showing a configuration of mobile station 300according to Embodiment 2 of the present invention. FIG. 14 differs fromFIG. 5 in that reporting cycle setting section 301 is added, PHR_datareport determination section 105 is changed to PHR_data reportdetermination section 302, and trigger information report determinationsection 108 is changed to trigger information report determinationsection 303.

Reporting cycle setting section 301 sets a reporting cycle of PHR_puschand a reporting cycle of trigger information so that the reporting cycleof trigger information is longer than the reporting cycle of PHR_pusch,and outputs the set reporting cycle of PHR_pusch to PHR_data reportdetermination section 302 and outputs the reporting cycle of triggerinformation to trigger information report determination section 303.

PHR_data report determination section 302 outputs PHR_pusch to datageneration section 109, in the cycle output from reporting cycle settingsection 301.

Trigger information report determination section 303 outputs triggerinformation to data generation section 109, in the cycle output fromreporting cycle setting section 301.

Here, the reason reporting cycle setting section 301 sets the reportingcycle of trigger information (PHR_pucch) longer than the reporting cycleof PHR_pusch, will be described below. Trigger information (PHR_pucch)used for switch of the transmission mode does not need to be reported asfrequently and accurately as PHR_pusch used for fine-tuned control suchas link adaptation, so that the reporting cycle of trigger informationis set longer than the reporting cycle of PHR_pusch.

For example, in the case where the reporting cycle of PHR_pusch is T[ms], the reporting cycle of trigger information is set as N×T [ms](here, N is a natural number). N is a parameter set per cell or permobile station, and is reported from base station 200 to mobile station300.

Methods of setting N include the following method. In a cell having alarge cell radius, because path loss increases, PHR of mobile station300 located at the cell edge is small, so that it is necessary to switchthe transmission mode. On the other hand, in a cell having a small cellradius, it is rare that mobile station 300 needs to switch thetransmission mode. Therefore, by setting N greater for a cell of asmaller cell radius so as to set the reporting cycle of PHR_pucchlonger, it is possible to switch the transmission mode appropriatelywith a small amount of signaling.

FIG. 15 is a sequence diagram showing a condition where mobile station300 shown in FIG. 14 transmits PHR_pusch and trigger information(PHR_pucch) to base station 200 shown in FIG. 8. As is clear from FIG.15, because trigger information (PHR_pucch) is reported in a long cycle,it is possible to suppress increase of signaling overhead.

As described above, according to Embodiment 2, by setting the reportingcycle of trigger information (PHR_pucch) longer than the reporting cycleof PHR_pusch, trigger information (PHR_pucch) is reported in a longcycle, making it possible to suppress increase of signaling overhead.

Embodiment 3

FIG. 16 is a block diagram showing a configuration of mobile station 400according to Embodiment 3 of the present invention. FIG. 16 differs fromFIG. 5 in that PHR_control calculation section 106 is changed toPHR_control calculation section 401, transmission mode setting section107 is changed to transmission mode setting section 402, PHR_data reportdetermination section 105 is changed to PHR_data report determinationsection 403, and trigger information report determination section 108 ischanged to trigger information report determination section 404.

PHR_control calculation section 401 calculates PHR_pusch+pucch (PHRcalculated based on transmission power required when a data channel anda control channel are FDM transmitted, as a reference) and PHR_pucch,based on a path loss level measured using a downlink pilot signal outputfrom demodulation section 103, and the number of frequency resourceblocks of a PUSCH, the MCS, power control information of a PUSCH, andpower control information of a PUCCH that are contained in thescheduling information output from demodulation section 103, and outputsthe calculated PHR_pusch+pucch and PHR_pucch to trigger informationreport determination section 404.

Transmission mode setting section 402 detects a command of a method ofmultiplexing a PUSCH and a PUCCH (TDM transmission mode or FDMtransmission mode) that is contained in the scheduling informationoutput from demodulation section 103, and outputs the result of thedetermination to trigger information report determination section 404,switch section 111, and PHR_data report determination section 403.

In the case where mobile station 400 is in the FDM transmission mode,PHR_data report determination section 403 does not report PHR_pusch. Onthe other hand, mobile station 400 is in the TDM transmission mode,PHR_data report determination section 403 reports PHR_pusch output fromPHR_data calculation section 104 to base station 200, based onpredetermined cycle T [ms] determined by base station 200 in advance.

In the case where mobile station 400 is in the FDM transmission mode,trigger information report determination section 404 determines toreport PHR_pusch+pucch output from PHR_control calculation section 401,based on cycle T [ms] determined by base station 200 in advance. In thecase where mobile station 400 is in the TDM transmission mode, in thesame way as in Embodiment 1, trigger information report determinationsection 404 performs comparison with a threshold value by comparing thePHR_pucch output from PHR_control calculation section 401 with apredetermined threshold value, and, based on the result of thecomparison with the threshold value, determines whether or not to reporttrigger information.

As described above, in the FDM transmission mode, PHR_data reportdetermination section 403 stops outputting the PHR_pusch, and triggerinformation report determination section 404 reports PHR_pusch+pucch astrigger information.

In the FDM transmission mode, if base station 200 can knowPHR_pusch+pucch, base station 200 can know the amount of transmissionpower of mobile station 400 that can be increased, so that it ispossible to control the transmission bandwidth and MCS of a PUSCH.Further, in the case where PHR_pusch+pucch becomes smaller (margin oftransmission power is reduced), by changing the transmission mode to theTDM transmission mode, it is possible to control transmission power ofmobile station 400 so as not to exceed the maximum transmission power.

By this way, in the FDM transmission mode, when a base station can knowPHR_pusch+pucch, it is possible to control switch of the transmissionmode, and control the transmission bandwidth and MCS of a PUSCH.

FIG. 17 is a sequence diagram showing a condition where mobile station400 shown in FIG. 16 transmits PHR_pusch and trigger information(PHR_pusch+pucch) to base station 200 shown in FIG. 8. As is clear fromFIG. 17, in the FDM transmission mode, by stopping reporting ofPHR_pusch, it is possible to suppress increase of signaling overhead.

As described above, according to Embodiment 3, in the FDM transmissionmode, by reporting PHR_pusch+pucch as trigger information, a mobilestation can suppress increase of signaling overhead.

In the case where the variable range of PHR to be reported forPHR_pusch+pucch is narrower compared to PHR_pusch, it is possible toreduce the number of signaling bits of PHR_pusch+pucch. For example,when the variable range of PHR is half, it is possible to reduce thenumber of signaling bits from six to three. By this means, it ispossible to further suppress increase of signaling overhead.

On the other hand, when the numbers of signaling bits of PHR_pusch+pucchand PHR_pusch are set the same, it is possible to use one signalingtransmission format. By this means, it is possible to simplify theprocessing of a mobile station or a base station.

In the case of calculating PHR_pusch+pucch, it is possible to performcalculation by adding the amount of increase of CM (=ΔCM) of the FDMtransmission with respect to TDM transmission, as shown in followingequation 10. By this means, it is possible to calculate PHR_pusch+pucchmore accurately.PHR_pusch+pucch=Pmax−(Ppusch+Ppucch)−ΔCM  (Equation 10)

Further, instead of reporting PHR_pucch or PHR_pusch+pucch, it ispossible to report a relative value with respect to PHR_pusch that isreported conventionally. By this means, it is possible to further reducethe amount of signaling.

Further, in the same way as PHR_pusch in LTE, in the case wherePHR_pucch is reported as MAC information of a PUSCH, it is possible tocalculate PHR_pucch based on the transmission power at the time oftransmitting a PUCCH at the closest time.

Further, instead of PHR_pucch to be newly reported, it is possible toreport information that can derive PHR_pucch (for example, g(Δ_(i)) ofequation 4 (transmission power control value for which closed loopcontrol is performed) or path loss (PL)).

Also, although cases have been described with the above embodiment asexamples where the present invention is configured by hardware, thepresent invention can also be realized by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (field programmable gate array) or a reconfigurable processor whereconnections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

Although a case has been described with the above embodiment where thepresent invention is configured as an antenna, the present invention isalso applicable to an antenna port.

The term, antenna port, refers to a theoretical antenna configured withone or a plurality of physical antennas. That is, an antenna port doesnot always refer to one physical antenna, and can also refer to, forexample, an array antenna configured with a plurality of antennas.

For example, in 3GPP LTE, how many physical antennas an antenna port isconfigured with is not prescribed, and an antenna port is prescribed asa minimum unit by which a base station can transmit a differentreference signal.

Further, an antenna port is also prescribed as a minimum unit with whichthe weight of precoding vector is multiplied.

The disclosure of Japanese Patent Application No. 2009-152647, filed onJun. 26, 2009, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

A radio communication apparatus and a radio communication method areapplicable to a mobile communication system, for example.

REFERENCE SIGNS LIST

-   101, 201 Antenna-   102, 202 RF reception section-   103 Demodulation section-   104 PHR_data calculation section-   105, 302, 403 PHR_data report determination section-   106, 401 PHR_control calculation section-   107, 402 Transmission mode setting section-   108, 303, 404 Trigger information report determination section-   109 Data generation section-   110 Control information generation section-   111, 204 Switch section-   112 TDM signal generation section-   113 FDM signal generation section-   114 CP addition section-   115, 212 RF transmission section-   121 Multiplexing section-   122, 131, 221, 231 DFT section-   123, 132 Mapping section-   124, 133, 224, 235 IDFT section-   203 CP removal section-   205 TDM signal demultiplexing section-   206 FDM signal demultiplexing section-   207 Control information decoding section-   208 Data decoding section-   209 Trigger information detection section-   210 Transmission mode control section-   211 Demodulation section-   222, 232 Demapping section-   223 Equalization section-   225 Demultiplexing section-   233 First equalization section-   234 Second equalization section-   301 Reporting cycle setting section

The invention claimed is:
 1. A radio communication apparatus comprising:a computing section which, in operation, computes a first power headroom(PHR), the first PHR being obtained by subtracting a transmit power fora data channel from a maximum transmit power, and computes a second PHR,the second PHR being obtained by subtracting the transmit power for thedata channel and a transmit power for a control channel from the maximumtransmit power; and a transmitting section which, in operation,transmits the first PHR and the second PHR, wherein when the datachannel and the control channel are simultaneously transmitted indifferent frequency bands, the second PHR is computed and transmitted.2. The radio communication apparatus according to claim 1, wherein whena simultaneous transmission of the data channel and the control channelin the different frequency bands is configured, the second PHR iscomputed and transmitted.
 3. The radio communication apparatus accordingto claim 1, wherein: when a simultaneous transmission of the datachannel and the control channel in the different frequency bands is notconfigured, the first PHR is computed and transmitted; and when thesimultaneous transmission of the data channel and the control channel inthe different frequency bands is configured, the second PHR is computedand transmitted.
 4. The radio communication apparatus according to claim1, wherein the data channel and the control channel are simultaneouslytransmitted by transmitting the data channel and the control channel ina same subframe.
 5. The radio communication apparatus according to claim1, wherein the maximum transmit power used for computing the second PHRhas a value obtained by subtracting an offset from the maximum transmitpower used for computing the first PHR.
 6. The radio communicationapparatus according to claim 1, wherein when the control channel is nottransmitted, the second PHR is transmitted as a MAC element in the datachannel.
 7. The radio communication apparatus according to claim 1,wherein a number of bits for the first PHR is same as a number of bitsfor the second PHR.
 8. The radio communication apparatus according toclaim 1, wherein the data channel is a physical uplink shared channel(PUSCH), and the control channel is a physical uplink control channel(PUCCH).
 9. A radio communication method comprising: computing a firstpower headroom (PHR), the first PHR being obtained by subtracting atransmit power for a data channel from a maximum transmit power;computing a second PHR, the second PHR being obtained by subtracting thetransmit power for the data channel and a transmit power for a controlchannel from the maximum transmit power; and transmitting the first PHRand the second PHR, wherein when the data channel and the controlchannel are simultaneously transmitted in different frequency bands, thesecond PHR is computed and transmitted.
 10. The radio communicationmethod according to claim 9, wherein when a simultaneous transmission ofthe data channel and the control channel in the different frequencybands is configured, the second PHR is computed and transmitted.
 11. Theradio communication method according to claim 9, wherein: when asimultaneous transmission of the data channel and the control channel inthe different frequency bands is not configured, the first PHR iscomputed and transmitted; and when the simultaneous transmission of thedata channel and the control channel in the different frequency bands isconfigured, the second PHR is computed and transmitted.
 12. The radiocommunication method according to claim 9, wherein the data channel andthe control channel are simultaneously transmitted by transmitting thedata channel and the control channel in a same subframe.
 13. The radiocommunication method according to claim 9, wherein the maximum transmitpower used for computing the second PHR has a value obtained bysubtracting an offset from the maximum transmit power used for computingthe first PHR.
 14. The radio communication method according to claim 9,wherein when the control channel is not transmitted, the second PHR istransmitted as a MAC element in the data channel.
 15. The radiocommunication method according to claim 9, wherein a number of bits forthe first PHR is same as a number of bits for the second PHR.
 16. Theradio communication method according to claim 9, wherein the datachannel is a physical uplink shared channel (PUSCH), and the controlchannel is a physical uplink control channel (PUCCH).